Selection Of Tree Species Inhibiting The Invasion Of Flaveria Bidentis

Flaveria bidentis(L.)Kuntze.is an alien weed that invaded into China in 1990s.It is still in the stage of rapid diffusion in China.Road is the path of its invasion and diffusion.The seed germination and seedling growth was affected by light and associated plant species,so it is important to find out the tree species that can inhibit the germination and growth of F.bidentis.The experiment was carried out around the scientific problem that corridor tree species can inhibit the seed germination and seedling growth of invasive plant F.bidentis.Firstly,the effect of litters extract from 23 species of northern boreal tree species on seed germination was compared and the best inhibitory effect was selected.Secondly,the effects of litters from selected tree species on the seedling growth of F.bidentis were carried out in pot experiment.The results will provide important reference value for the use of boreal tree species to block the diffusion of the invasive plant,and provide a basis for planting of the greenbelt in the diffusion area of F.bidentis at the same time.The results were as following:The concentration of litter extracts of 23 kinds of tree species(0,5%,10%,15%,20%)had allelopathic effect on seed germination rate and root length of F.bidentis.The inhibitory effect increased with the increasing of the concentration of litter extracts.The inhibitory effects Ailanthus altissima Swingle,Prunus CerasiferaEhrhar f.atropurpurea Rehd.,Populus tomentosa Carr.and Syringa oblata Lindl.on seed germination rate of F.bidentis were bigger than the others.Meanwhile,the germination rate of F.bidentis treated with 5%litter extracts of the four plant species was lower than that with 10%litter extracts,respectively.Their generation rates of F.bidentis were less than 7%when treated with 10%litters water extract.The seeds of F.bidentis did not sprout when treated with 15%litters water extract.With the increase of the concentration,the inhibitory effect of water extract of the litters of S.oblata.and P.tomentosa on the root length became more significantly.The root length of F.bidentis was 0 when treated with 10%or 15%litters water extract of S.oblate or P.tomentosa.The bud length of F.bidentis was 0 when treated with 5%and 10%litters water extract of P.tomentosa.According to the germination rate,root length and seedling length of F.bidentis S.oblata and P.tomentosa had stronger inhibitory than the others.The effects of different litter factors(mode,concentration,decay)on seed germination and seedling growth of P.tomentosa were carried out in pot experiment.Compared with the mixed treatment,mulch treatment can significantly reduce the germination rate of F.bidentis,and its germination rate shows a significant trend of decreasing with the increase of litter concentration.On the whole,the biomass in the mixture treatment was lower than that in the mixture.The plant height in the mixture treatment was lower than that of mulch treatment,and the plant height of non-rot treatment was significantly lower than that rot treatment.The decomposition of litters inhibited the root growth,especially root surface area and root volume.The effects of different litter factors(mode,concentration,decay)on seed germination and seedling growth of S.oblata were carried out in pot experiment.Compared with the undecayed treatment,the germination rate of F.bidentis was significantly reduced in the decayed treatment.Its germination rate in mulch treatment was significantly lower than that in mixture treatment.On the whole,the biomass of the F.bidentis in undecayed treatment was lower than that in decayed treatment,and the plant height in undecayed treatment was significantly reduced compared to that in decayed treatment.The biomasses of F.bidentis in the 150g/m~2 and 300g/m~2 of undecayed mulch treatment were significantly lower than that of decayed mulch treatment,respectively.